ABSTRACT
Background: The radiological impact of the use of phosphate fertilizers in soil
is due to the internal irradiation of the lung by the alpha particles, short
lived radon-thoron progeny and the external irradiation of the body by gamma
rays emitted from radionuclides in situ. This paper describes the results of
gamma spectrometric measurements of the concentration of the natural
radionuclides namely 226Ra, 232Th and 40K in the soil samples collected from the
fields where a variety of phosphate fertilizers are being used by the farmers to
enhance the crop yield. Materials and Methods: The experimental work utilizes
actual measurements of 226Ra, 232Th and 40K using gamma spectrometry and radon
concentration and exhalation rates measurements using solid state nuclear track
(LR-115, Type- II plastic) detectors to asses a first order exposure risk for
the persons working in the fields where lot of fertilizers are being used to
enhance crop yield in terms of occupational exposure. Results: The concentration
of Radium, Thorium and Potassium in the mixed soil sample from crop fields is
16.2±0.22, 68.1±1.44 and 875.0±9.68 Bq/kg, where as in barren soil sample is
9.1±0.13, 59.4±1.45 and 668.4±8.01 Bq/kg respectively. The radium equivalent
activity (Raeq) in the mixed soil sample from crop fields is 225.9 Bq/kg, where
as in barren soil sample is 193.1 Bq/kg. The values of absorbed dose and annual
effective dose (indoors and outdoors) are found to vary from 90.87 nGyh-1 to
119.71nGyh-1, 0.45mSv/y to 0.59mSv/y and 0.11mSv/y to 0.15mSv/y respectively in
soil sample from crop fields, whereas the value of absorbed dose and annual
effective dose (indoors and outdoors) is 92.29 nGyh-1, 0.45mSv/y, 0.11
respectively in soil sample collected from barren land. The radon concentration
and exhalation rates have also been reported. Conclusion: The activity
concentration, exhalation rate and absorbed dose were found to increase
substantially with the use of phosphate fertilizers and it varies from sample to
sample. The radium equivalent activities in all the soil samples were found to
be lower than the limit (370 Bq/kg) set in the Organization for Economic
Cooperation and Development (OECD) report and the dose equivalent is within the
safe limit of 1mSv/y.
Kant K, Upadhyay S, Sonkawade R, Chakarvarti S. Radiological risk assessment of use of phosphate fertilizers in soil. Int J Radiat Res 2006; 4 (2) :63-70 URL: http://ijrr.com/article-1-224-en.html